The invention relates to a cabinet hinge whose supporting wall-related part in the form of an elongated supporting arm is mounted on a mounting plate which can be fastened to the supporting wall of a cabinet and is pivotally coupled, through a jointed mechanism, to a door-related hinge part which can be fastened to the door. In hinges of this kind, the supporting arm has in its end portion pointing into the interior of the cabinet case an open-mouthed longitudinal slot through which passes the shaft of a mounting screw driven into the mounting plate; a tap is provided in the front end of the supporting arm pointing out of the cabinet case interior, into which tap a setscrew is threaded, on whose bottom end on the mounting plate side there is provided, on a neck-like portion of reduced diameter, a holding head, defined in part by partially spherical surfaces, and having an increased diameter, which is inserted into a narrowed opening, provided in the mounting plate, of a slot open at the jointed-mechanism end which secures the holding head against lifting away.
Cabinet hinges having a supporting wall-related part which is made adjustable by a circular disk-like holding head in this manner are known (DE-OS No. 26 14 447), and their use is increasing on account of the possibility which they provide for the relatively quick and simple hanging of a door equipped with such hinges on the corresponding supporting wall of the cabinet case. These hinges have been further developed by the applicant by modifying the holding head from a circular disk-like configuration to a substantially full sphere so that they allow a still greater length for adjustment for the door overlap (DE-OS No. 33 02 312). Mounting plates pertaining to these known hinges have heretofore been made exclusively from die-cast metal, namely from zinc alloy (Zamak), and thus, in comparison with the simpler mounting plates made by stamping from sheet metal used in other hinge types, they are relatively expensive, because, due to the lower strength of the alloy, the walls of the mounting plates made from zinc die-casting metal must be made decidedly thicker than in the case of mounting plates pressed from sheet steel, and the result is a comparatively greater weight, i.e., a greater consumption of the zinc die-casting alloys which are comparatively expensive in themselves.
The invention is addressed to the problem of further developing the known hinge described in the beginning such that it will be usable both in conjunction with mounting plates of zinc die-casting alloy and with mounting plates made by stamping, because of improved strength in the area of the engagement of the holding head in the corresponding slot in the mounting plate. Moreover, the supporting arm of the new hinge is to be usable without modification or alteration on the mounting plates of hinges of the former kind in which the holding head on the setscrew for the adjustment of the door overlap is made in the form of a sphere.
Setting out from a hinge of the kind described in the beginning, this problem is solved in accordance with the invention in that the holding head has the form of a body developed from a sphere having an annular circumferential groove formed in rotational symmetry with the longitudinal central axis of the setscrew. The modified holding head is therefore developed from the spherical holding head in such a manner that it fits the known mounting plates designed for hinges with a spherical holding head. Furthermore, the annular circumferential groove additionally provided in the holding head also permits the further development of the mounting plates in the longitudinal slot area such that additional form-fitting engagement is achieved between the holding head and the longitudinal slot and thus increased strength.
In a preferred further development of the invention, the circumferential groove has a triangular cross section with the apex of the triangle pointing toward the longitudinal axis of the setscrew. At the same time the circumferential groove is preferably formed in the half of the holding body which adjoins the neck portion, i.e., the bottom half of the holding head still has the shape of a hemisphere.
The annular surface defining the neck side of the substantially hemispherical surface of the holding body lies, however, preferably in a plane passing through the spherical center of the holding body at right angles to the longitudinal central axis of the setscrew.
Alternatively, the circumferential groove can also have a substantially trapezoidal cross section expanding from the inside out, in which case it is then recommendable to provide it approximately in the equatorial area of the holding body.
If the hinge of the invention is to be used together with a mounting plate made of metal by die casting, the configuration is made such, in accordance with the invention, that the slot in the mounting plate has underneath its narrowed opening a cross section which is substantially complementary to the cross-sectional surface of the holding head in a section plane passing through the longitudinal central axis of the setscrew.
If the supporting arm of the hinge of the invention is, on the other hand, to be fastened on a mounting plate made by stamping from sheet metal, the configuration of the mounting plate is best made such that the slot provided in it to receive the holding head is formed by a longitudinal slot, open at the end pointing toward the jointed mechanism, in its wall that is covered by the supporting arm, this wall's width being approximately equal to or only slightly greater than the diameter of the neck portion joining the setscrew to the holding head. The form-fitting holding of the setscrew to the mounting plate is therefore provided in the area of the neck portion, while the securing of the supporting arm against lifting away from the mounting plate is provided by the holding head reaching under the longitudinal slot, and the securing against the opposite movement, i.e., toward the mounting plate, is provided by the face of the setscrew itself projecting radially beyond the neck portion.
The length of the neck portion is preferably slightly smaller than the thickness of the metal at the edges of the mounting plate defining the longitudinal slot, the edges of the longitudinal slot being then chamfered at their underside facing the holding head such that the chamfer is, in cross section, approximately tangential to the portion of the holding head adjoining the neck portion. This prevents the danger of damage to the holding head in the area of engagement with the bottom arris of the longitudinal slot or of the rapid wear of this arris, which would be the case if the arris were to be made simply sharp.